Section 90.279 - Power limitations applicable to the 421-430 MHz band(a) Base station authorizations in the 421-430 MHz band will be subject to Effective Radiated Power (ERP) and Effective Antenna Height (EAH) limitations as shown in the table below. ERP is defined as the product of the power supplied to the antenna and its gain relative to a half-wave dipole in a given direction. EAH is calculated by subtracting the Assumed Average Terrain Elevation (AATE) as listed in table 7 of § 90.619 from the antenna height above mean sea level. Limits of Effective Radiated Power (ERP) Corresponding to Effective Antenna Heights (EAH) of Base Stations in the 421-430 MHz Band
| Effective antenna height (EAH) in meters (feet) | Maximum effective radiated power (ERP) (watts) |
| 0-152 (0-500) | 250 |
| Above 152-305 (above 500-1000) | 150 |
| Above 305-457 (above 1000-1500) | 75 |
| Above 457-610 (above 1500-2000) | 40 |
| Above 610-762 (above 2000-2500) | 20 |
| Above 762-914 (above 2500-3000) | 15 |
| Above 914-1219 (above 3000-4000) | 10 |
| Above 1219 (above 4000) | 5 |
(b) The maximum transmitter power output that will be authorized for control stations is 20 watts.52 FR 6157, Mar. 2, 1987, as amended at 58 FR 44957, Aug. 25, 1993